A tuning fork A of unknown frequency produces 5 beats/s with a fork of known frequency 340 Hz

Question

A tuning fork A of unknown frequency produces 5 beats/s with a fork of known frequency 340 Hz. If frequency of fork A is lower than that of the other, what is the original frequency of fork A?

Smart Achievers · Accepted Answer

(1)

Let $f_{1}$ be the frequency heard by wall, $f_{1} = (\frac{v}{v - v_{c}}) f_{0}$

Here, $v$ = Velocity of sound,

$v_{c}$ = Velocity of Car,

$f_{0}$ = actual frequency of car horn

Let $f_{2}$ be the frequency heard by driver after reflection from wall.

$f_{2} = (\frac{v + v_{c}}{v}) f_{1} = (\frac{v + v_{c}}{v - v_{c}}) f_{0}$

$\Rightarrow 480 = [\frac{345 + v_{c}}{345 - v_{c}}] 440 \Rightarrow \frac{12}{11} = \frac{345 + v_{c}}{345 - v_{c}}$

$\Rightarrow v_{c} = 54 k m / h r$

Solution

Q.
A tuning fork A of unknown frequency produces 5 beats/s with a fork of known frequency 340 Hz. If frequency of fork A is lower than that of the other, what is the original frequency of fork A

1 335 Hz

2 338 Hz

3 345 Hz

4 342 Hz

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